1. Field of the Invention
The invention relates to a power transmitting device and a power transfer system.
2. Description of Related Art
As is described in Japanese Patent Application Publication No. 2010-172084 (JP 2010-172084 A) and Japanese Patent Application Publication No. 2010-239777 (JP 2010-239777 A), there is known a contactless power supply system that contactlessly transmits electric power.
In recent years, a road-to-vehicle power supply system in which a plurality of power transmitting devices are embedded in a road surface and a power receiving device provided at a vehicle contactlessly receives electric power from any one of the power transmitting devices has become a focus of attention.
For example, a road-to-vehicle power supply system described in Japanese Patent Application Publication No. 2006-166570 (JP 2006-166570 A) includes power receiving-side communication means for transmitting information, such as positional information, toward a power transmitting device, a power receiving antenna, the power transmitting device, power transmitting antennas and power transmitting-side communication means. The power transmitting device causes some of the power transmitting antennas to irradiate microwaves on the basis of the received information.
Generally, when a vehicle receives electric power in a charging space, the vehicle initially approaches the charging space and stops, and then receives electric power.
Here, the road-to-vehicle power supply system described in JP 2006-166570 A includes the plurality of power transmitting-side communication means, and causes some of the power transmitting antennas to irradiate microwaves on the basis of the position of one of the power transmitting-side communication means, which has received the information from the power receiving-side communication means.
In other words, it is indispensable that the above-described road-to-vehicle power supply system includes the plurality of power transmitting-side communication means. Therefore, the power transmitting device becomes very expensive. However, if the number of power transmitting-side communication means is reduced, there occurs a positional deviation between the power receiving antenna and the power transmitting antennas, with the result that power transfer efficiency decreases.